Roll stabilization free gyro system



Sept. l1, 1962 w. E. BENNETT ETAL 3,053,699

ROLL STABILIZATION FREE GYRO SYSTEM 5 Sheets-Sheet 1 Filed April 25, 1960 Sept. 1l, 1962' w. E. BENNETT ETAL 3,053,099

Rom. STABILIZATION FREE GYRo SYSTEM Filed April 25, 1960 5 Sheets-Sheet 2 Sept. 11, 1962 w. E. BENNETT ETAL ROLL STABILIZATION FREE GYRO SYSTEM 5 Sheets-Sheet 3 Filed April 25, 1960 Sept. 11, 1962 w. E. BENNETT ETAL 3,053,099

ROLL STABILIZATION FREE GYRo SYSTEM Filed April 25, 1960 5 Sheets-Sheet 4 Sept. 11, 1962 w. E. BENNETT ETAL ROLL STABILIZATION FREE GYRO SYSTEM 5 Sheets-Sheet 5 Filed April 25, 1960 United States Fatent @time 3,653,099 Patented Sept. l1, 1962 3,053,059 ROLL STABILIZATIUN FREE GYRQ SYSTEM William E. Bennett, Encino, John Nooteboom, Pacific Palisades, and Stanley K. Weissberg, Sherman Oaks, Calif., assignors to Telecomputing Corporation, Van Nuys, Calif., a corporation of California Fiied Apr. 25, 1960, Ser. No. 24,507 12 Claims. (Cl. 74-5.4)

This invention relates to inertial navigation apparatus and, more particularly, to gyroscopic means for maintaining a stable platform in a moving vehicle. Many rockets are spin-stabilized and the present invention has particular application to such vehicles.

Free gyros have heretofore been utilized for determining the attitude of a missile when the missile is rotating at relatively low speeds. These gyros provide the attitude information without stabilizing a platform. Due, however, to the spinning, the gyroscope drift rate is high, and due to the limited freedom of the gyro gimbals, the reference is easily lost. When the missile is spinning at a relatively high speed, such as 20 cycles per second, the drift is so great that free gyros are effectively inoperable. Stabilized platforms have not been utilized in high spinning vehicles because of the tremendous power requirements required to stabilize the platform. The faster the missile spins, the less torque is available from a given rotor for stabilizing the platform. Moreover, the larger the motor utilized to stabilize the platform, the greater is its weight and inertia and, accordingly, the greater is the required torque. For these reasons, stabilized platforms for fast spinning missiles have heretofore been impractical and suitable means for accurately providing missile attitude information has been unavailable.

In a specific illustrative embodiment of this invention, a stabilized platform is provided for a high speed spinning missile utilizing relatively small motors and power requirements. A roll servo is provided which stabilizes the roll platform by reacting against an inertial iiy-wheel. The inertial fly-wheel is maintained effectively stationary about its rotational axis with respect to three dimensional space by driving it at a speed equal to but in a direction opposite to the missile spinning motion.

The roll servo system essentially operates under substantially static conditions requiring minimum power, with the torques required to overcome bearing frictional losses due to the high rotational velocity being supplied to the y-wheel by a relatively low power air gap torquer. Both the roll servo and the air gap torquer are relatively low power motors. The system operates under substantially static conditions because the roll servo reacts against the stationary y-wheel instead of the spinning missile airframe. The instantaneous rotating .speed of the ily-Wheel changes quite rapidly due to accelerations of the missile but the speed restores relatively slowly because a low power torquer is utilized. The fly-wheel, accordingly, restores slowly to its effective stationary position in space.

The fly-wheel has a dual function in that it dampens the reaction of the roll servo as well as serving as an effectively static reaction member for the roll servo. By damping the roll servo, oscillations and rapid movements of the platform are avoided.

Further features of this invention pertain to the provision of a two degree-of-freedom gyro as the roll sensing element to avoid a drift of the -system due to any wobble motion of the missile as it -spins about its roll axis.

Further advantages and features of this invention will become apparent upon consideration of the following description when read in conjunction with the drawing wherein:

IGURE 1 is a sectional view through the gyro system of this invention depicting the fly-wheel and coupling to the roll servomotor;

FIGURE 2 is a sectional View taken along lines 2 2 of FIGURE 1 illustrating the roll gyro and the pitch-yaw oym;

c FIGURE 3 is a sectional view taken along lines 3-3 of FIGURE 2 showing the roll gyro and its bearing support means on the -roll gimbal;

FIGURE 4 is a sectional view taken along lines 4--4 of FIGURE 1 depicting the tachorneter and gear coupling to the fly-wheel;

FIGURE 5 is a partial side view taken along lines 5-5 of FIGURE 4 illustrating the pitch-yaw gyro and lsynchro pickoff;

FIGURE 6 is a functional representation of the gyro system of this invention illustrating the functional arrange of the various components of the system;

FIGURE 7 is a perspective view of the gyro system of this invention; and

FIGURE 8 is a perspective view of the roll gimbal structure forming the stabilized platform in the gyro system of this invention.

Referring rst to FIGURE 6, the gyro system of this invention is mounted on a frame 10 orf a spinning vehicle or missile. The spinning motion of the missile and the frame IG therewith is about the roll axis 15 of the missile at an illustrative speed of 20 revolutions per second.

In the functional representation illustrated in FIGURE 6, the main shafts 12 and 14 of the gyro system are respectively rotatably mounted by bearings 13 and 16 on the frame l@ of the missile. Actually, as shown more particularly in FIGURES 1 and 2, the shafts 12 and 14 are rotatably mounted in a gyro housing 50 which is attached to the frame 10 and, therefore, rotatable with the missile. The housing 50, which may be hermetically sealed, is substantially cylindrical in shape having illustrative dimensions of an eight inch diameter and an overall length of ten inches. The -shape and external appearance of the housing 5G is shown particularly in FIGURE 7. The weight of the gyro system, including the housing 50l and the various component-s enclosed thereby, is quite small, illustratively, less than 20` pounds. The size and weight of the gyro system is, accordingly, very suitable to missile applications.

The housing 50 includes a front plate 51 which is attached to the main portion of the housing 50 by fastening means or screws 52 (FIGURE l). The main portion of the housing 50 also has a number of access openings 53 which are covered after the various components are assembled in the housing 50 by a cylind-rical sleeve 54 which may be soldered onto the housing 50. The housing S0, including the front plate 51 and the sleeve 54, forms a rigid, hermetically sealed structure which is attached or affixed to the frame 10 of the spinning missile. The housing Si), therefore, rotates about the roll axis 1S, illustrated in FIGURES 1, 3 and 7 as well as FIGURE 6, together with the frame 10 of the missile. The two shafts 12 and 14 mentioned above, are aligned along the roll axis 15 at opposite ends of the housing 50 and are respectively supported -by the bearings I3 and I6 on the housing Sti. Actually, as shown particularly in FIGURE 1, the bearings 13 are supported by a resolver rsupport plate 55 which is attached to the housing 50 by fastening means or screws 56 (FIGURE 1). In addition to the bearings i3, the plate 55 also supports a roll gimbal resolver 58, which may be a conventional type and which develops a signal indicative of the angular position of the shafts 12 and 14 with respect to the housing 50. The roll gimbal resolver 58, which ts into a cylindrical seat 5g at one end of the housing 50, is illustrated functionally in FIG- URE 6.

At the other end of the housing 50 in FIGURE 1, the

Due to the normal frictional losses, the torquer 26 provides a small continuous drive to the ilywheel 25 to maintain it stationary in space. If such a torque is not provided, the bearing friction gradually speeds up the flywheel 25 until it rotates together with the housing 50.

If the flywheel 25 is maintained roll-stationary in space, the full torque of the servomotor 32 is available for stabilizing the platform or gimbal structure 65. The torquer 26 may be set to provide a predetermined small torque to overcome normal bearing friction when the servomotor is not developing a torque. Any rotation of the flywheel 25 about the roll axis 15 reduces the available torque because the servomotor 32 must first compensate for the movement of its reaction member, the ilywheel 25. It is the reserve torque of the servomotor which determines the stabilization characteristic of the platform. If the flywheel 25 is stationary, the servomotor 32 reacts against the stationary flywheel 25 so that an eectively static or non-spinning stabilization arrangement is achieved.

As long as the roll gimbal structure 65 is not accelerated so as to increase bearing friction and the missile spinning rate remains the same, the roll signal produced by the roll gyroscope 2t) does not vary the torque delivered by the servomotor 32. When the portion of the vehicle or missile carrying the housing 5t) is accelerated either due to stage separation or about its roll axis 15, the llywheel 25 and the gimbal structure 65 are accelerated and a roll signal is developed. Any change of the roll attitude of the platform or structure 65 either due to accelerations or frictional effects, develops a roll signal which is provided to the servomotor 32. The servomotor 32 develops a torque for returning the structure 65 to its normal position by reacting against the flywheel 25 and at the same time it generates a tachometer signal for returning the flywheel 25 to its normal or stationary position in space. The torque generated by the air gap torquer 26 corrects both for the acceleration which rotates the flywheel 25 as Well as the platform 65 and for the effect of the servomotor 32 reacting against the flywheel 25. The torquer 26, therefore, requires reserve torque facility to bring the flywheel 25 back to standstill after a random acceleration. The reserve torque required to stabilize the flywheel 25 is twenty times that available from the torquer 26 so that the flywheel 25 is returned slowly to standstill after a fast speed-up due to the random acceleration. A relatively small torquer 26 as well as servomotor 32 may, accordingly, be utilized.

The greater the mass of the flywheel 25, the less variation occurs in its speed due to any acceleration. However, the illustrative moment of inertia of the flywheel 25 of one-half that of the gimbal structure 65 is selected because of a number of other considerations. For example, the larger the weight of the flywheel 25, the greater is the weight of `the housing package. In some applications, the weight factor is an important consideration. Moreover, the flywheel 25 has a dual function in that it functions as a damping device for the servomotor 32. The gimbal structure 65, therefore, does not move rapidly responsive to rapid changes of torque delivered by the servomotor 32 because of the damping provided by the flywheel 25. The smaller the moments of inertia of the flywheel 25, the greater the damping because a greater portion of the servomotor torque is expended in rotating the flywheel 25. The moment of inertia of the flywheel 25, accordingly, is a compromise of these factors and at the illustrative Value, is one-half that of the roll gimbal structure `65 and its supported components.

The gyro system of this invention is suitable for applications in which the housing 50 may be subjected to accelerations as high as lOO-G. For example, as indicated above, the gyro system of this invention may be utilized as part of a multi-stage rocket and when the different stages separate, very high loads or accelerations are transmitted to the housing 50 which tend to brake the gimbal Vstructure 65 and the -llywheel 25. Any acceleration which tends to change the roll position of the gimbal structure 65 changes the roll signal generated by the roll gyroscope 20 to energize the servomotor 32 to maintain the attitude of the :structure 65. Both the braking load and the torque developed by the servomotor cause the ilywheel 25 to rotate in space in a direction opposite to the direction of rotation of the housing 5G. The tachometer signal, however, gradually returns the flywheel 25 to its standstill position. The servomotor 32 reacts relatively fast to keep the platform or structure 65 stabilized and the vflywheel 25 returns slowly to its standstill position.

Functionally, the operation is quite similar to the slow charging of a `battery with small amounts of energy so that it can provide a large amount of energy during a brief interval. 'I'he flywheel 25 functions as the energy storage device releasing it in bursts upon random accelerations.

As described above, When the gyro system returns to a steady state condition, the output of the air gap torquer 26 is equal to the friction of the bearings for maintaining the flywheel 25 -and the gimbal structure 65- stationary in space. Due to the constant bearing friction, the flywheel 25 tends to speed up and -use up the torque of the servomotor 32. The air gap torquer 26, however, maintains the flywheel 25 at standstill to maintain the torque of the servomotor 32 `available for stabilizing the platform or structure 65.

A two degree of freedom roll gyroscope 2li is utilized instead of a single degree of freedom gyroscope to remove any components due to any wobble of the missile about the roll axis 15. If a single degree of freedom gyroscope is used, a `drift factor is introduced bty kinematic rectification so that the platform y65 gradually rotates in space.

The stabilized platform or structure 65 supports, as indicated above, a pitch-yaw gyroscope 17 in addition to the roll gyroscope 26. The pitch-yaw gyroscope 17 is supported, as indicated particularly in FIGURE 2, between the two horizontal sections 65a and 65!) of the housing 65. The pitch-yaw gimbal which supports the gyroscope 17 is mounted on a shaft 102 which is pivotally supported in the bearings 103 and 104. The upper end of the shaft 102 is supported in a housing extension 14,2 of the upper bracket 65a. A pitch-yaw pickoif i100', which may be a synchro resolver, is utilized to generate the pitch-yaw signals and couple them through lbrushes 108 to the terminals 107. The terminals 107 may be coupled to an amplifier, not shown, in the amplifier section 73 and the amplified pitch-yaw signal may be provided through the slip ring assembly 60 in FIGURE l to the cable 61. The various components on the gimbal 90 shown in FIGURE 2 are part of the caging mechanism for the gimbal 90. The caging mechanism may be conventional.

In this manner, pitch and yaw signals are provided from a roll stabilized platform 65 indicating the attitude of the missile. In addition, as described above, the roll gimbal resolver 58 provides signals indicative of the roll of the missile. The platform 65 is accurately roll-stabilized even though the missile is spinning at a high rate by utilizing relatively small and light components.

Although this invention has been disclosed and illustrated with reference to particular applications, the principles involved are susceptible of numerous other applications which will be apparent to persons skilled in the art. For example, the particular disclosed pickoif means or caging equipment is merely illustrative. The invention is, therefore, to be limited only `as indicated by the scope of the appended claims.

We claim:

l. In a spinning vehicle, a rotatable platform pivoted to rotate about the axis of rotation of the spinning vehicle, a rotatable reaction flywheel pivoted to rotate about the axis of rotation of the spinning vehicle, a servomotor mounted on said platform and coupled to said flywheel for angularly positioning said platform with respect to said flywheel, and gyroscopic means mounted on said platform and coupled to said servomotor for detecting any change in the angular position of said platform about said axis and for controlling said servomotor in accordance therewith to return said platform to its original position.

2. In a spinning vehicle, a rotatable platform pivoted to rotate about the axis of rotation of the spinning vehicle, a rotatable reaction flywheel pivoted to rotate about the axis of rotation of the spinning vehicle, a servomotor mounted on said platform and coupled to said flywheel for angularly positioning said platform with respect to said flywheel, gyroscopic means mounted on said piatform and coupled to said servomotor for detecting any change in the angular position of said platform about said axis and for controlling said servomotor in accordance therewith to return said platform to its original position, means coupled to said servomotor for generating a signal indicative of the speed of said servomotor, and a torquer coupled to said generating means and to said flywheel for torquing said flywheel in accordance with the generated signal from said generating means whereby said flywheel is returned to a substantially stationary position about said axis after any movement of said flywheel therefrom.

3. In a spinning vehicle subject to accelerations, a stabilized platform pivoted to rotate about the axis of rotation of the spinning vehicle, a rotatable reaction member for said platform, means mounted on said platform for providing a signal indicative of an angular change of position of said platform, and means coupled to said platform and to said reaction member and responsive to said signal from said providing means for exerting a torque between said platform and said reaction member tending to rotate them in opposite directions.

4. In a spinning vehicle, a stabilized roll-free gyro system, including, a roll gyro gimbal having a roll axis about which it is pivoted, a rotatable reaction member for said gyro gimbal, torquing means coupled to said reaction member for returning said reaction member to a predetermined roll position after any displacement therefrom, and means mounted on said gyro gimbal for detecting any displacement in the roll position of said gyro gimbal and for energizing said torquing means in accordance therewith.

5. In a spinning vehicle, a substantially static reaction system, including, a normally non-rotating pivoted inertial member rotatable about the spinning axis of the vehicle, torquing means coupled to said member and effectively responsive to any torque which rotates said member for stabilizing said member about the spinning axis by slowly reducing the rotation of said member to standstill, a platform stabilized about the spinning axis of the vehicle, and a servomotor coupled between said member and said platform for stabilizing said platform by reacting against said member.

6. In a spinning vehicle, a substantially static reaction system, including, a normally non-rotating pivoted inertial member rotatable about the spinning axis of the vehicle, torquing means coupled to said member and effectively responsive to any torque which rotates said member for stabilizing said member about the spinning axis by slowly reducing the rotation of said member to standstill, a platform stabilized about the spinning axis of the vehicle, a servomotor coupled between said member and said platform for stabilizing said platform by reacting against said member, means coupled to said servomotor and said torquing means for developing a signal indicative of the stabilizing torque developed -by said servomotor and for introducing the signal to said torquing means, and gyroscopic means mounted on said platform and electrically coupled to said servomotor for detecting any change in angular position of said platform about the spinning axis of the vehicle and for developing a control signal in S accordance therewith for introduction to said servomotor.

7. In a spinning vehicle, a substantially static reaction system, including, a normally non-rotating pivoted inertial member rotatable about the spinning axis of the vehicle, torquing means coupled to said member and effectively responsive to any torque which rotates said member for stabilizing said member about the spinning axis by slowly reducing the rotation of said member to standstill, a platform stabilized about the spinning axis o-f the vehicle, a servomotor coupled between said member and said platform for stabilizing said platform by reacting against said member, and means coupled to said servomotor and said torquing means for developing a signal indicative'of the stabilizing torque developed by said servomotor and for introducing the signal to said torquing means.

8. In a spinning vehicle, a rotatable platform pivoted to rotate about the axis of rotation of the spinning vehicle, a rotatable reaction flywheel pivoted to rotate about the axis of rotationV of the spinning vehicle, a servomotor mounted on said platform having a rotor, a gear train coupled between said rotor and said flywheel so that any torque generated by said servomotor tends to rotate said platform and said flywheel in opposite directions, and gyroscopic means mounted on said platform and coupled to said servomotor for detecting any change in the angular position of said platform about said axis and for controlling said servomotor in accordance therewith.

9. ln a spinning vehicle, a rotatable platform pivoted to rotate about the axis of rotation of the spinning vehicle, a rotatable reaction flywheel pivoted to rotate about the axis of rotation of the spinning vehicle, a servomotor mounted on said platform having a rotor, a gear train coupled between said rotor and said flywheel so that any torque generated by said servomotor tends to rotate said platform and said flywheel in opposite directions, gyroscopic means mounted on said platform and coupled to said servomotor for detecting any change in the angular position of said platform about said axis and for controlling said servomotor in accordance therewith, and torquing means coupled to said flywheel for returning said flywheel to a stationary position after being rotated by the reaction of said servomotor generating a torque to rotate said platform.

10. In a spinning vehicle, a rotatable platform pivoted to rotate about the axis of rotation of the spinning vehicle, a rotatable reaction flywheel pivoted to rotate about the axis of rotation of the spinning vehicle, a servomotor mounted on said platform having a rotor, a gear train coupled between said rotor and said flywheel so that any torque generated by said servomotor tends to rotate said platform and said flywheel in opposite directions, gyroscopic means mounted on said platform and coupled to said servomotor for detecting any change in the angular position of said platform about said axis and for controlling said servomotor in accordance therewith, said flywheel having a moment of inertia less than the moment of inertia of said platform together with the servomotor and gyroscopic means supported thereby so as to dampen the rotational movements of said platform, and torquing means coupled to said flywheel for returning said flywheel to a stationary position after being rotated by the reaction of said servomotor generating a torque to rotate said platform.

l1. In a spinning vehicle, a rotatable platform pivoted to rotate about the axis of rotation of the spinning vehicle, a rotatable reaction flywheel pivoted to rotate about the axis of rotation of theY spinning vehicle, a servomotor mounted on said platform and coupled to said flywheel for angularly positioning said platform with respect to said flywheel, and means for detecting any change in the angular position of said platform about said axis and for controlling said servomotor in accordance therewith to return said platform to its original position.

12. In a spinning vehicle subject to accelerations, a

9 10 stabilized member pivoted to rotate about the axis of References Cited in the le of this patent rotation of the spinning vehicle, a rotatable reaction UNITED STATES PATENTS member for said stabilized member, means for providing 2 383 409 Newell Aug 21 1945 a Signal indicative of an angular Change 0f pOSitOll 0f Said 2417689 Johnson u Marl 18 1947 stabilized member, and means IGSPODSV@ t0 Said Signal 5 2,802,364 Gievers n Aug' 13 1957 from Said providing means for exerting a torque between I l said stabilized member and said reaction member tending FOREIGN PATENTS to rotate them in opposite directions. 167,071 Australia Feb. 22, 1956 

